One of the most effective therapeutic methods for sleep apnea syndrome is a nasal continuous positive airway pressure (CPAP) method, in which a respiratory assist device is adopted to supply positive pressure gas at about 400 to 2000 Pa to the nasal cavity of a user during sleep. In recent years, devices with a function to control a pressure automatically responding to an occurrence state of apnea during therapy have also been used. One of the most effective therapeutic methods for ventilatory insufficiency is a nasal intermittent positive pressure ventilation (NIPPV) method, in which a respiratory assist device is adopted to supply intermittent positive pressure gas at about 400 to 2400 Pa to the nasal cavity of a user.
When these types of equipments are used for treatments, a nasal respiratory mask system composed of a nasal mask (also called “nasal mask cushion” or “cushion”) tightly sealing the face of a user and having a hollow shape and of a frame retaining the nasal mask at a predetermined position and having a mechanism to connect with a hose that leads a positive pressure gas is generally used to continuously maintain positive pressure to the nasal cavity of a user. Such a nasal mask system then tightly seals the face of a user by the tension of a strap (including a headgear) (see, for example, Patent Document 1).
Patent Document 2 discloses mounting a brace composed of a wire engageable with a frame section in a nasal respiratory mask system. Such a brace may serve as a mounting site for a strap (including a headgear), but has no function to reinforce the fixing a nasal mask to the frame.
Patent Documents 3 and 4 disclose a forehead support supporting a nasal mask system, in which a forehead pad is attached to such a forehead support. However, such a forehead support is attached to a connection section of a hose for respiratory gas.
Patent Document 5 describes a member called a circular “frame” mounted on a surrounding of “shell/cushion”. However, such a “frame” can be engaged only with a channel provided in “shell/cushion”, but has no function to fix a cushion to a shell. Even in preferred embodiments, both shell and cushion are primarily integrated in one piece.
Patent Documents 6 also describes a member called circular “frame” mounted on a surrounding of a “curved body”, but lacks a function to fix a nasal mask to the “curved body”.
Patent Document 1: Japanese Patent Laid-Open Publication No. H11-397.
Patent Document 2: WO 02/045784
Patent Document 3: WO 03/035156
Patent Document 4: WO 03/059427
Patent Document 5: WO 04/096332
Patent Document 6: WO 03/035156